The Avro 504 is a British biplane that was first introduced in 1913. Designed by the Avro company, it was primarily used as a trainer aircraft during World War I. Its simple design and reliable performance made it popular among pilots, helping to train many who would go on to serve in the war. The Avro 504 featured a wooden frame and fabric covering, with a distinctive two-wing structure that provided stability in flight. It was powered by various engines over its production run, allowing for different performance levels. The aircraft played a significant role in early aviation history and influenced future aircraft designs.